Having a high volume blood transfusion or many blood transfusions in a short period of time.

What To Think About

More than one blood test may be needed to see if blood calcium
levels are not normal.

Low blood levels of calcium may be caused by low levels of
protein (albumin) in the blood, because about half of all calcium in the blood
is attached to albumin. For this reason, an ionized calcium level (which is not
attached to albumin) and a blood albumin level may also be measured. To learn more, see the topic
Total Serum Protein.

Other tests that may be done to find the cause of abnormal blood
calcium levels include blood tests for
parathyroid hormone (PTH), chloride, acid phosphatase,
alkaline phosphatase, and vitamin D.